I'm not saying that I think the Korg is a bad unit, but as far as handheld units go, I personally see an internal harddrive as more of a liability these days because a) it's a power hog compared to similar designed compact flash-based units, b) more moving parts usually means more that might go wrong. (One fairly meaningless-to-this-thread point of reference is that the SD702 lasts 7 to 8 hours on a NPF975 battery, while the 722 lasts 4 to 5 hours.)
So, while I don't own an R-09HR, I do own a Marantz PMD-620. It lasts almost 5 hours on 2 AAs and I'm currently writing to a 16GB SD card...but 32GB cards work as well. If I were to do it over, I'd get the R-09HR (since they're out now, but weren't when I bought the 620) which is known to have a very low noise floor, although some people have told me that my 620 has the same guts as the R-09 (really don't know if that's true or not tho.)
Don't intend to diss any MR-1 owners...just trying to offer an opinion on why I didn't go with the Korg.